CORE B SUMMARY The Muscle Tissue/Cell Culture/Diagnostics Core of the Iowa Wellstone Muscular Dystrophy Cooperative Research Center is a multifaceted laboratory that serves as a local, national and international resource for research on muscular dystrophy and other neuromuscular diseases. This Core has two major goals. Firstly, it has established and will expand a tissue and cell culture Repository to support basic and translational research efforts. Currently, this Repository contains muscle biopsies from more than 8500 patients with neuromuscular disorders, as well as cryopreserved fibroblasts from more than 425 patients with myopathic disease, predominantly muscular dystrophies. Well-characterized tissues and cells from the Core are made available to research investigators at Iowa as well as other academic centers across the USA and around the world. Secondly, the Core provides specialty diagnostic services that are not readily available through clinical laboratories, and facilitates research on and the development of new diagnostic tests for eventual transfer into clinical laboratories. These diagnostic services are very closely integrated with clinical laboratory testing carried out in the Department of Pathology at the University of Iowa. Together, Core B and the Department of Pathology services provide state-of-the-art diagnostic testing for patients seen at the University of Iowa Hospitals and Clinics, and for patients referred to Iowa from throughout the USA and from several other countries. This infrastructure provides key support for clinical trials of neuromuscular disease.